Vertebrate Head Skeleton Flashcards Preview

BIOL 3326 Exam 2 > Vertebrate Head Skeleton > Flashcards

Flashcards in Vertebrate Head Skeleton Deck (22):
1

skull

brain case
upper jaw
lower jaw

2

head skeleton

neurocranium
dermatocranium
splanchnocranium

3

Neurocranium

= entire braincase in Chondrichthyes; chondrocranium

lesser contribution of neurocranium in other Gnathostomes:
focus on tetrapods
4 ossification centers

bones derived from neurocranium are ENDOCHONDRAL

4

ossification centers of neurocranium

occipital center
sphenoid center
ethmoid center
otic center

5

occipital center of ossification of neurocranium

location: posterior floor of brain

surrounds foramen magnum; yields up to 4 bones: supraoccipital, exoccipital (2), basioccipital --> ankylose

occipital condyles: from various occipital bones

"fish" and reptiles: one condyle (basioccipital with some contribution of exoccipital)

Enlarged exoccipitals (reduced contributions of other occipital bones): 2 condyles -- mammals

6

sphenoid center of ossification of neurocranium

location: central and lateral floor

basisphenoid, presphenoid

sella turcica = upper region of basisphenoid

Alisphenoid (greater wing) in mammals forms from the upper jaw cartilage and fuses with other sphenoid bones (thus a composite bone)

7

ethmoid center of ossification of neurocranium

location: anterior and medial floor

turbinate cartilages (turbinate conchae/nasal conchae) in amniotes

nasal conchae may/may not ossify

cribriform plate and crista galli: ethmoid

8

otic center of ossification of neurocranium

cartilaginous otic capsule (encloses inner ear organs)

"otic bones": prootic, opisthotic, epiotic (one on each side)

in tetrapods: otic bones fuse - form petrosal bone

mammals: petrosal unites with squamosal bone (membrane bone) to form temporal bone

Note: temporal bone = composite bone = contribution from different ossification centers

9

Dermatocranium

all membrane bone, no endochondral contribution

forms:
-side and roof of cranium enclosing brain
-"palate" bones
-upper jaw bones
-lower jaw bones

10

Dermatocranium series

vault series
orbital series
temporal series
palatal series
facial series
mandibular series

11

Vault series of the dermatocranium

"roofing bones"

most are paired: frontal, parietal, post-parietal (=interparietal when fused) -- occasionally present in humans

seen as "extra bone" in humans = Wormian bone

12

Orbital series of the dermatocranium

circumorbital bones

define eye orbit

lacrimal, prefrontal, postfrontal, postorbital, jugal

13

Temporal series of the dermatocranium

behind orbit; posterolateral wall of braincase)

temporal fenestrae associated with temporal series (and jugal of orbital series)

fenestrae function???

lateral position: squamosal and quadratojugal (contribute to cheek)

medial position: supratemporal, intertemporal, tabular

14

Primary palate bones of the dermatocranium

applied to ventral floor of neurocranium

vomer, palatine, pterygoid, ectopterygoid, parasphenoid

teeth usually present on primary palate bones in teleosts, amphibians, non-avian reptiles

Note: primary palate is not the hard palate!

primary palate = bony roof of buccal cavity in amphibians = bony roof nasal passage in amniotes

hard palate in amniotes = bony roof of mouth; hard palate = secondary palate

15

facial series of the dermatocranium

mostly membrane bones of upper jaw

premaxilla, maxilla, nasal

form in dermis and fuse with primary palate in T thus upper jaw = part of the skull in tetrapods

premaxilla and maxilla bear teeth

16

palatoquadrate cartilage

upper jaw in Chondrichthyes

not homologous to maxilla

forms:
-alisphenoid
-quadrate bone (posterior region of upper jaw)

17

mandibular series of the dermatocranium

membrane bones of lower jaw

lateral: dentary, splenial, angular, surangular

medial: coronoid, prearticular

18

Splanchnocranium

"visceral cranium"

skeleton of pharyngeal arches incorporated into head skeleton

=embryonic upper jaw cartilage (palatoquadrate) and its replacement bone

embryonic lower jaw cartilage (Meckel's cartilage) and its replacements bone

19

Meckel's cartilage

lower jaw cartilage

forms:
-articular bone (posterior region of lower jaw)

20

articulation of jaw

quadrate and articular represent articulation of jaw in tetrapods

mammal articulation: squamosal (mandibular fossa) and dentary (mandibular condyle)

21

quadrate bone

derived from palatoquadrate cartilage

in amphibians and reptiles: articulates with articular bone in lower jaw

in mammals: becomes incus = anvil (middle ear)

i.e. incus is homologous to lower jaw in amphibians/reptiles

amphibians/reptiles have 1 middle ear bone, mammals have 3

22

articular bone

from Meckel's cartilage

in amphibians and reptiles: articulates with quadrate in upper jaw

in mammals: becomes malleus = hammer (middle ear)

i.e. malleus is homologous to upper jaw in amphibians/reptiles

amphibians/reptiles have 1 middle ear bone, mammals have 3